Production processes of H(D) atoms in the reactions of NO(A 2Σ+) with C2H2, C2H4, H2O, and their isotopic variants Original Re

The production of H(D) atoms was identified in the reactions of NO(A 2Σ+) with C2H2, C2H4, H2O, and their isotopic variants. By measuring the Doppler profiles, the translational energies of H(D) atoms were determined. As for C2H2 and H2O, around 1/4 of the NO(A2Σ+) energy is partitioned into the translational mode, while the ratio is around 1/7 for C2H4. Such a large partitioning of the available energy into the translational mode cannot be explained by a C–H(O–H) bond rupture after an energy transfer. Nitrogen compounds, such as ONC2H and HONO, must be produced as pair products. The measured translational energies are much larger than those statistically expected, suggesting that the intermediate species are short-lived. No large isotope effect was observed in the average translational energies or in the relative yields. Quantum effects, such as tunneling, do not play important roles. Ab initio molecular orbital calculations were carried out to characterize these reactive processes.